A student has been convicted of orchestrating cyber attacks that brought down several payments websites, causing losses of £3.5m to PayPal alone.

Christopher Weatherhead, 22, who went under the internet name of Nerdo, was an integral part of the Anonymous group, which caused websites to crash by flooding them with requests and messages as part of Operation Payback.

The websites were then directed to a page displaying the message: "You've tried to bite the Anonymous hand. You angered the hive and now you are being stung."

The distributed denial of service attacks carried out by the computer hackers targeted PayPal, MasterCard and Visa.

It was a co-ordinated response to the companies' decision to stop handling payments for the WikiLeaks website after its mass publication of classified documents in 2010.

The cyber attacks cost PayPal £3.5m. The other companies did not disclose how much the offensive had cost them.

The court heard that Weatherhead had sent a message to an acquaintance saying he thought it could run to millions.

Weatherhead was studying at Northampton University when he joined the cyber campaign.

London's Southwark Crown Court heard that PayPal was attacked after it decided not to process payments on behalf of the Wau Holland Foundation, an organisation involved in raising funds for WikiLeaks.

For 10 days in December 2010, PayPal was the victim of a series of attacks "which caused considerable damage to its reputation and loss of trade".

The group also attacked the Ministry of Sound, the British Recorded Music Industry (BPI) and the International Federation of the Phonographic Industry (IFPI) at other dates because of their anti-piracy stances.

Weatherhead had denied a charge of conspiring to impair the operation of computers between August 1, 2010 and January 22, last year, but was convicted by a jury.

Three other defendants had already pleaded guilty to the charge. They are Ashley Rhodes, 27, from south London; Peter Gibson, 24, from Hartlepool; and Jake Birchall, 18, from Chester.

Judge Peter Testar said: "This is a serious offence and I hope the defendant understands that."